The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. Over the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric sizes (i.e., the smallest component that can be created using a fabrication process) have decreased.
Micro-electro mechanical system (MEMS) devices have recently been developed. MEMS devices include devices fabricated using semiconductor technology to form mechanical and electrical features. The MEMS devices are implemented in accelerometers, pressure sensors, microphones, actuators, mirrors, heaters, and/or printer nozzles.
A MEMS device formed in a semiconductor process requires forming a movable structure with a certain mass. In prior approaches, a thin film layer is provided and patterned to form a movable part that is coupled to the remaining structures by flexible supports, which allow the movable part to move in certain directions. However, the thin film structure will induce residue stress on the MEMS device and degrade the performance of the MEMS device. It is desirable to develop a MEMS device with an alternate thin film structure so as to achieve better performance.